Whether during an emergency situation or during a routine flight operation, knowledge of an angle of attack of an aircraft can help a pilot of the aircraft perform safer and more stable manoeuvers. Because pilots are often inundated with information, an indication of an angle of attack relative to an optimum and/or critical angle of attack can be even more useful. For instance, while an instrument indicating an angle of attack is useful to a pilot that knows the aircraft well enough to immediately understand how the indication relates to an optimum and/or critical angle of attack for the particular aircraft in a particular configuration and/or in certain circumstances, an indication of the relationship of an angle of attack to an optimum and/or critical angle of attack is useful to a pilot regardless of how well the pilot knows the aircraft. Consequently, it would be beneficial to have an angle of attack indication system and method for determining and indicating an angle of attack of an aircraft relative to an optimum and/or critical angle of attack of the aircraft.
Many existing angle of attack systems require dedicated sensors and/or knowledge of aerodynamic parameters of an aircraft. These limitations make it complex to install these systems onto an existing aircraft and/or render the systems ineffective and/or unreliable when aerodynamic and/or other changes and/or modifications are made to an aircraft already having such a system. Consequently, it would be beneficial to have an angle of attack indication system and method that does not require a dedicated sensor. It would further be beneficial to have an angle of attack indication system that utilizes a calibration process to estimate aerodynamic parameters of the aircraft so that the system can be installed on a variety of existing aircraft and so that the system can remain useful and reliable even after the aircraft is modified by performing a new calibration process.
Because pilots often rely on information such as an angle of attack indication, it is imperative that the information be as accurate as possible, as reliable as possible, and as up-to-date as possible. Consequently, it would be beneficial to have an angle of attack indication system and method that obtains information from navigation sensors that are more reliable than, have lower noise than, and have faster responses than dedicated angle of attack sensors. And because inaccurate information can be more dangerous to a pilot than no information at all, it would be beneficial to have an angle of attack indication system and method that provides an indication of an anomaly and/or does not display an angle of attack indication if an anomaly is detected.
A variety of existing systems for and/or methods of calculating an angle of attack of an aircraft include one or more dedicated sensor. For instance, U.S. Published Application No. 2014/0230539, the entire disclosure of which is incorporated herein by reference, teaches a special probe having a rotating fin; U.S. Published Application No. 2014/0053644, the entire disclosure of which is incorporated herein by reference, teaches a wall tap port inlet; U.S. Pat. No. 8,653,990, the entire disclosure of which is incorporated herein by reference, teaches angle of attack vanes; U.S. Pat. No. 8,620,495, the entire disclosure of which is incorporated herein by reference, teaches independent probes; U.S. Pat. No. 8,104,339, the entire disclosure of which is incorporated herein by reference, teaches ports that are coupled to pressure sensors via ducts, U.S. Pat. No. 7,377,159, the entire disclosure of which is incorporated herein by reference, teaches a plurality of mass flow sensors; U.S. Pat. No. 6,940,425, the entire disclosure of which is incorporated herein by reference, teaches pressure sensors; and U.S. Pat. No. 6,012,331, the entire disclosure of which is incorporated herein by reference, teaches unique probes. Furthermore, U.S. Pat. No. 5,089,968, U.S. Pat. No. 7,406,369, and U.S. Pat. No. 6,772,976, the entire disclosures of which are incorporated herein by reference, teach physical sensors for calculating and/or otherwise determining an angle of attack for an aircraft.
Other existing systems for and/or methods of calculating an angle of attack of an aircraft require knowledge of aerodynamic parameters of an aircraft that are not always available or that cannot be easily determined. U.S. Pat. No. 6,928,341, the entire disclosure of which is incorporated herein by reference, teaches a system that requires a detailed aircraft aerodynamic model. The system further requires measurements of aerodynamic control surfaces. U.S. Pat. No. 4,769,759, the entire disclosure of which is incorporated herein by reference, teaches a system that requires aerodynamic data for the aircraft, the initial gross weight of the aircraft, and the position of the aircraft's center of gravity. U.S. Pat. No. 4,046,341, the entire disclosure of which is incorporated herein by reference, teaches a system that requires an aerodynamic model of an aircraft.
Still other existing systems for and/or methods of calculating an angle of attack of an aircraft require knowledge of only inertial data and are thus not so accurate in windy and turbulent conditions. U.S. Pat. No. 6,273,370, the entire disclosure of which is incorporated herein by reference, teaches a system that requires inertial sensors, such as accelerometers, to compute an inertial estimation of the angle of attack. The system is primarily directed towards being used as a possible back-up device for systems that include one or more dedicated sensor and/or as sources for correction curves. U.S. Pat. No. 3,948,096 and U.S. Pat. No. 6,791,208, the entire disclosures of which are incorporated herein by reference, teach a system that utilizes accelerometers to derive the angle of attack of an aircraft independent of the aerodynamic characteristics of the aircraft. Such a system does not require, and would gain no benefit from, a calibration flight, so it gives only a rough estimation of the angle of attack.